As a method for forming a high-quality semiconductor film, there is an epitaxial growth technique which grows a single-crystal film on a substrate, such as a wafer, using vapor phase growth. In a vapor phase growth apparatus using the epitaxial growth technique, a wafer is placed on a support portion in a reaction chamber which is maintained at atmospheric pressure or reduced pressure.
Then, process gas, such as source gas which will be a raw material for forming a film, is supplied from an upper part of the reaction chamber to the surface of the wafer in the reaction chamber while the wafer is being heated. For example, the thermal reaction of the source gas occurs at the surface of the wafer and an epitaxial single-crystal film is formed on the surface of the wafer.
The characteristics of the epitaxial single-crystal film formed on the surface of the wafer depend on the temperature of the wafer. Therefore, it is preferable to improve the uniformity of the temperature at the wafer surface.
JP H7-58040 discloses a vapor phase growth apparatus in which a protrusion is provided on a susceptor for supporting a wafer in order to reduce the deformation of the wafer and to uniformly heat the wafer.